Determining Bitloading Profiles based on SNR Measurements

1. A method for identifying a plurality of modulation tiers for grouping network elements communicating over an orthogonal frequency division multiplexed (OFDM) channel having a plurality of subcarriers, the method comprising: defining a metric associated with a measurable characteristic of the network elements; collecting measurements associated with the measurable characteristic for a plurality of the network elements communicating over the OFDM channel, each measurement corresponding to at least one of the plurality of network elements and a respective one of the plurality of subcarriers, wherein the measurements collected for the plurality of network elements communicating over the OFDM channel includes: receiving digitally modulated signals returned from the plurality of network elements; and calculating the measurements for each of the plurality of network elements based on downstream or upstream parameters by headend equipment that characterizes the digitally modulated signals returned from the plurality of network elements, wherein characterizing the digitally modulated signals returned from a network element to calculate the measurements comprises: measuring an initial total power loading which is equal to total power of radio frequency (RF) energy present within a bandwidth of interest on an OFDM channel; instructing a cable modem to transmit a first test signal on the OFDM channel at initial total power loading; monitoring the first test signal at a headend of the OFDM channel; and measuring at the headend at least one of modulation error ratio (MER0), signal-to-noise ratio (SNR0), packet error rate (PER0), or bit error rate (BER0); for each of the plurality of network elements, translating the measurements collected for the respective network element in to at least one network element metric value; dividing the OFDM channel into a plurality of modulation tiers each based on a range of the network element metric values determined from the measurements collected for the plurality of network elements, wherein each modulation tier is associated with a modulation level; for each of the plurality of network elements, comparing the respective at least one network element metric value to the range of metric values associated with each of the plurality of modulation tiers; and distributing each of the plurality of network elements to a modulation tier in the plurality of modulation tiers based on the comparison of the at least one network element metric value to the range of metric values associated with each of the plurality of modulation tiers.

2. The method of claim 1 , further comprising generating the profile of the OFDM channel based on an identification of the plurality of modulation tiers and the metric values associated with each of the plurality of modulation tiers.

3. The method of claim 1 , wherein the metric associated with a measurable characteristic of the network elements is a characteristic of at least one of a cable modem, a cable modem termination system (CMTS), or the OFDM channel.

4. The method of claim 1 , wherein the measurable characteristic of the network elements is at least one of a modulation error rate, a signal-to-noise ratio, a packet error rate, a bit error rate, or a number of cable modems.

5. The method of claim 1 , wherein the metric associated with the measurable characteristic of the network elements defined for each of the plurality of tiers includes at least one of: a target of the measurable characteristic for a respective tier, a threshold of the measurable characteristic for each respective tier, an average of the measurable characteristic for a respective tier, a minimum of the measurable characteristic for a lowest tier, a maximum of the measurable characteristic for a highest tier, a statistical distribution of the measurable characteristic among the tiers, a percentage amount of the measurable characteristic for a respective tier, or an equal distribution of the measurable characteristic for each tier.

6. The method of claim 1 , wherein the metric values associated with the metric defined for each of the plurality of modulation tiers includes at least one of a range of values, values calculated from the measurements for the plurality of network elements, user-defined values, cable operator-defined values, statistical approach values, a total number of cable modems divided by the number of tiers, or a percentage of the total number of cable modems.

7. The method of claim 1 , wherein distributing each of the plurality of network elements to a modulation tier based on the comparison of measurement collected for the plurality of network elements to the metric values associated with the plurality of modulation tiers is a distribution based on at least one a cable mode (CM) count per tier, a target CM measurement per tier, a target modulation measurement per tier, a statistical measurement per tier, or defined for each tier based on a standard deviation curve.

8. The method of claim 1 , wherein each of the plurality of modulation tiers has a threshold value of the measurable characteristic defined for each of the plurality of subcarriers.

9. The method of claim 8 , wherein the profile further includes a predetermined scheme for allocating marginal network elements to a tier in the plurality of modulation tiers.

10. The method of claim 1 , wherein a marginal network element is a network element in the plurality of network elements that is associated with two or more of the plurality of tiers.

11. The method of claim 10 , wherein the marginal network element is associated with two or more of the plurality of tiers due to having at least one first metric value for a first subcarrier that corresponds to one of the plurality of modulation tiers and at least one second metric value for another subcarrier that corresponds to another one or more of the plurality of modulation tiers.

12. The method of claim 10 , wherein the allocation of a marginal network element to a tier in the plurality of modulation tiers is based on a predetermined scheme.

13. The method of claim 12 , wherein the predetermined scheme comprises a scheme for allocating the marginal network element to a tier based on at least one of: a closest fit, wherein the marginal network element is allocated to a tier with the smallest difference between the network element metric value for each OFDM subcarrier and a metric value associated with each of the plurality of modulation tiers for each OFDM subcarrier; a primary tier, wherein the tiers are each defined by upper metric boundary values and lower metric boundary values, and the marginal network element is allocated to the tier in which the majority of the network element metric values for the plurality of subcarriers map; the lowest tier in which the marginal network element has a metric value; or the highest tier in which the marginal network element has a metric value.

14. The method of claim 1 , wherein the network element is at least one of a cable modem, set top box, television equipped with set top box, data over cable service interface specification (DOCSIS) terminal device, or a media terminal adapter (MTA).

15. The method of claim 1 , wherein profile defined for the plurality of modulation tiers in the OFDM channel are defined with initial values and are dynamically adjustable.

16. The method of claim 15 , wherein the profile is adjusted by adjusting each of the plurality of modulation tiers based on at least one of: improved signal-to-noise ratio (SNR) performance of at least one of the subcarriers, calculations based on forward error correction (FEC), or increasing the modulation order of a subcarrier.

17. A cable television network complying at least in part with a Data Over Cable Service Interface Specification (DOCSIS) protocol, the cable television network comprising: a plurality of cable modems; a cable modem termination system (CMTS) in communication with the plurality of cable modems, said CMTS having a receiver configured to monitor the test signals and a processor configured to record measurements; one or more orthogonal frequency division multiplexed (OFDM) channels, the CMTS communicating with the plurality of cable modems over the one or more orthogonal frequency division multiplexed (OFDM) channels, the network configured to define a metric associated with a measurable characteristic of the network elements for at least one OFDM channel; the cable modem termination system (CMTS) configured to: remotely instruct a network element to transmit test signals at a pre-determined power level on a return path of a test channel; collect measurements associated with the measurable characteristic for a plurality of the network elements communicating over the OFDM channel, each measurement corresponding to at least one of the plurality of network elements and a respective one of the plurality of subcarriers, wherein the measurements collected for the plurality of network elements communicating over the OFDM channel includes: receiving digitally modulated signals returned from the plurality of network elements; and calculating the measurements for each of the plurality of network elements based on downstream or upstream parameters by headend equipment that characterizes the digitally modulated signals returned from the plurality of network elements, wherein characterizing the digitally modulated signals returned from a network element to calculate the measurements comprises: measuring an initial total power loading which is equal to total power of radio frequency (RF) energy present within a bandwidth of interest on an OFDM channel; instructing a cable modem to transmit a first test signal on the OFDM channel at initial total power loading; monitoring the first test signal at a headend of the OFDM channel; and measuring at the headend at least one of modulation error ratio (MER0), signal-to-noise ratio (SNR0), packet error rate (PER0), or bit error rate (BER0); for each of the plurality of network elements, translate the measurements collected for the respective network element in to at least one network element metric value; divide the at least one OFDM channel into a plurality of modulation tiers each based on a range of the network element metric values determined from the measurements collected for the plurality of network elements, wherein each modulation tier is associated with a modulation level; for each of the plurality of network elements, compare the respective at least one network element metric value to the range of metric values associated with each of the plurality of modulation tiers; and allocate each of the plurality of network elements to a tier in the plurality of modulation tiers based on the comparison of the at least one network element metric value to the range of metric values associated with each of the plurality of modulation tiers.

18. A non-transitory computer-readable storage medium having stored thereon instructions that, when executed, cause a processor to: define a metric associated with a measurable characteristic of the network elements for at least one OFDM channel; collect measurements associated with the measurable characteristic for a plurality of the network elements communicating over the OFDM channel, each measurement corresponding to at least one of the plurality of network elements and a respective one of the plurality of subcarriers, wherein the measurements collected for the plurality of network elements communicating over the OFDM channel includes: receiving digitally modulated signals returned from the plurality of network elements; and calculating the measurements for each of the plurality of network elements based on downstream or upstream parameters by headend equipment that characterizes the digitally modulated signals returned from the plurality of network elements, wherein characterizing the digitally modulated signals returned from a network element to calculate the measurements comprises: measuring an initial total power loading which is equal to total power of radio frequency (RF) energy present within a bandwidth of interest on an OFDM channel; instructing a cable modem to transmit a first test signal on the OFDM channel at initial total power loading; monitoring the first test signal at a headend of the OFDM channel; and measuring at the headend at least one of modulation error ratio (MER0), signal-to-noise ratio (SNR0), packet error rate (PER0), or bit error rate (BER0); for each of the plurality of network elements, translate the measurements collected for the respective network element in to at least one network element metric value divide the at least one OFDM channel into a plurality of modulation tiers each based on a range of the network element metric values determined from the measurements collected for the plurality of network elements, wherein each modulation tier is associated with a modulation level; for each of the plurality of network elements, compare the respective at least one network element metric value to the range of metric values associated with each of the plurality of modulation tiers; and allocate each of the plurality of network elements to a tier in the plurality of modulation tiers based on the comparison of the at least one network element metric value to the range of metric values associated with each of the plurality of modulation tiers.